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Supporting Information Wiley-VCH 2008 69451 Weinheim, Germany

An Isolable Side-on Superoxonickel Complex [LNi(O 2 )] with Planar Tetracoordinate Ni II and Its Conversion to the Unusual LNi(μ-OH) 2 NiL Complex with Planar Tetracoordinate and Tetrahedral Ni II Sites (L = ß-Diketiminato)** Shenglai Yao, Eckhard Bill, Carsten Milsmann, Karl Wieghardt and Matthias Driess* A. Experimental Section General Considerations: All experiments and manipulations were carried out under dry oxygen-free nitrogen (except for the synthesis of compound 1) using standard Schlenk techniques or in an MBraun inert atmosphere drybox containing an atmosphere of purified nitrogen. Solvents were dried by standard methods and freshly distilled prior to use. The starting material 1 [1] (L = CH{(CMe)(2,6- i Pr 2 C 6 H 3 N} 2 ) was prepared according to literature procedure. 1 H-NMR spectra were recorded on Bruker Spectrometer AS 200. Chemical shifts of the deuterated solvents in 1 H NMR data: benzene-d 6 : δ(c 6 D 5 H) = 7.15 ppm. Single-Crystal X-ray Structure Determinations: Crystals were each mounted on a glass capillary in perfluorinated oil and measured in a cold N 2 flow. The data of Compounds 1, and 3 were collected on an Oxford Diffraction Xcalibur S Sapphire at 150 K (Mo-Kα radiation, λ = 0.71073 Å). The structures were solved by direct methods and refined on F 2 with the SHELX-97 [2] software package. The positions of the H atoms were calculated and considered isotropically according to a riding model. The oxygen atoms O1a and O1b in 3 are each statistically disordered over two orientations in a population ratio of 0.51:0.49. CCDC 687060 (1) and 687061 (3) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

Magnetic Susceptibility Measurement: Magnetic susceptibility data were measured from powder samples of solid material in the temperature range 2-300 K with a SQUID susceptometer with a field of 1.0 T (MPMS-7, Quantum Design, calibrated with standard palladium reference sample, error < 1%). The experimental data were corrected for underlying diamagnetism by use of tabulated Pascal s constants, [3, 4] as well as for temperature-independent paramagnetism (TIP). The susceptibility and magnetization data were simulated with our own package julx for exchange coupled systems. [5] The simulations are based on the usual spin-hamilton operator for mononuclear complexes with spin S=1/2 for 1 and S = 1 for 3: H ˆ = gβs v ˆ B v + D [ S ˆ 2 z 1/3 S(S +1) + E /D( S ˆ 2 x S ˆ 2 y )] eq. 1 where g is the average electronic g value, and D and E/D are the axial zero-field splitting and rhombicity parameters. Intermolecular interactions were considered by using a Weiss temperature, Θ W, as perturbation of the temperature scale, kt' = k(t-θ W ) for the calculation. Powder summations were done by using a 16-point Lebedev grid. EPR Measurement: X-band EPR derivative spectra were recorded on a Bruker ELEXSYS E500 spectrometer equipped with the Bruker standard cavity (ER4102ST) and a helium flow cryostat (Oxford Instruments ESR 910). Microwave frequencies were calibrated with a Hewlett-Packard frequency counter (HP5352B), and the field control was calibrated with a Bruker NMR field probe (ER035M). The spectra were simulated with the program GFIT (by E.B.) for the calculation of powder spectra with effective g values and anisotropic line widths (Gaussian line shapes were used). Compound 1 A solution of 2 (0.59 g, 0.56 mmol) in toluene (40 ml) was cooled to -78 C. The N 2 atmosphere in the flask was exchanged to dried oxygen. After stirring for 15 min, the reaction mixture was allowed to warm to room temperature and stirred further for 30 min in the oxygen atmosphere. In the course of stirring the colour of the solution changed from brown red to green. Volatiles were removed in vacuo, and the residue was washed with n-hexane (20 ml) and then extracted with toluene (50 ml). After concentration and cooling to -20 C for 12 h, compound 1 crystallized from the solution as green crystals (0.48 g, 0.94 mmol, 84 %). M.p. 139 C (decomp.) 1 H NMR (200.13 MHz, C 6 D 6, 298K): δ = -3.7 (1H), 1.0 (16H), 3.2 (12H), 6.6 (4H), 7.8 (2H), 11.6 (6H). EI-MS: m/z (%): 508.4 (5, [M] + ), 476.4 (100, [M-O 2 ] + ). Elemental analysis (%): calcd for C 29 H 41 N 2 NiO 2 : C, 68.5; H, 8.1; N, 5.5. Found: C, 68.8; H, 7.9; N, 5.3. UV-vis (toluene): 360 nm (15000 M -1 cm -1 ), 420 nm (365 M -1 cm -1 ), 460 nm (190 M -1 cm - 1 ), 590 nm (170 M -1 cm -1 ), 980 nm (430 M -1 cm -1 ). IR (KBr, cm -1 ): ν = 444 (w), 635 (w), 718 (w), 723 (w), 761 (m), 770 (w), 800 (m), 936 (m), 971 (m, 16 O- 16 O str.), 1030 (w), 1056 (w), 1100 (w), 1180 (w), 1235 (w), 1254 (m), 1319 (s), 1372 (s), 1438 (s), 1455 (m), 1530 (s), 1556 (m), 1584 (w), 1635 (w), 2866 (m), 2924 (m), 2961 (s), 3055 (w).

65 60 55 50 45 40 %T 35 30 25 20 15 10 5 ν(o 16 -O 16 ) 971 cm -1 ν(o 18 -O 18 ) 919 cm -1 1600 1400 1200 1000 Wavenumbers (cm-1) Figure 1. IR spectrum of 1. Assignment of the O-O vibrational modes in accord with isotope labelling experiments. 800 600 Figure 2: X-band EPR spectrum of 1 in frozen toluene at 50 K (microwave frequency 9.43216 GHz, power 6.3 mw, modulation 0.3 mt/ 100kHz). The red line is a powder simulation with anisotropic g values as indicated.

Figure 3: Temperature dependence of the effective magnetic moment of solid 1 with applied field B = 1 T. The red line is a simulation with S = 1/2 and g av = 2.08. The decrease of μ eff below 10 K is due to the combined effect of field saturation and weak intermolecular interaction according to a Weiss temperature of about Θ W = -0.1 K. The experimental data have been corrected for a TIP contribution to χ of 150x10-6 emu. Compound 3 Method A. A solution of 2 (0.47 g, 0.45 mmol) in toluene (30 ml) was cooled to -20 C. The N 2 atmosphere in the flask was exchanged to dried N 2 O. After stirring for 10 min, the reaction mixture was allowed to warm to room temperature and stirred further for 2h in the N 2 O atmosphere. In the course of stirring the colour of the solution changed from brown red to brown yellow. Volatiles were removed in vacuo, and the residue was extracted with n- hexane (50 ml). After concentration and cooling to -20 C for 12 h, compound 3 crystallized from the solution as green crystals (0.21 g, 0.21 mmol, 47 %). Method B. To a cooled (-78 C) solution of 2 ( 0.14 g, 0.26 mmol) in toluene (5 ml) was added a solution of 1 (0.14g, 0.13 mmol) in toluene (5 ml) with stirring. After the addition the reaction mixture was allowed to warm to room temperature and stirred further for 2 h. Volatiles were removed in vacuo, and the residue was extracted with n-hexane (25 ml). After concentration and cooling to -20 C for 12 h, compound 3 crystallized from the solution as green crystals (0.10 g, 0.10 mmol, 39 %). Method C. To a solution of 1 ( 0.16 g, 0.31 mmol) in toluene (10 ml) was added PPh 3 ( 0.16 g, 0.62 mmol) at room temperature. After stirring for 12 h, the 1 H and 31 P NMR spectra showed that compound 3 and Ph 3 P=O were formed along with unconsumed PPh 3 (Ph 3 P=O: PPh 3 1:1). Volatiles were removed in vacuo, and the residue was extracted with n-hexane (25 ml). After concentration and cooling to -20 C for 12 h, compound 3 crystallized from the solution as green crystals (0.05 g, 0.05 mmol, 33 %). M.p. 284 C (decomp.) 1 H NMR (200.13 MHz, C 6 D 6, 298K): δ = -16.7(m), -7.9(m), 1.4(d), 3.9(d), 4.0(t), 6.5 (br.), 11.1(m), 35.7(br.). EI-MS: m/z (%): 986.5 (8, [M] + ), 969.5 (2, [M-OH] + ),476.4 (100, [1/2M-OH] + ). Elemental analysis (%): calcd for C 58 H 84 N 4 Ni 2 O 2 : C, 70.6; H, 8.6; N, 5.7. Found: C, 70.3; H, 8.5; N, 5.5. UV-vis (n-hexane): 380 nm (9200 M -1 cm -1 ), 400 nm (8800 M -1 cm -1 ). IR (KBr, cm -1 ): ν = 458 (w), 519 (w), 741 (w), 762 (m), 797 (m), 867 (w), 935 (w), 1026 (w), 1057 (w), 1100 (w), 1179 (m), 1254 (m), 1318 (m), 1362 (m), 1404 (s), 1436 (s), 1461 (s), 1531 (s), 1654 (w), 2868 (m), 2928 (m), 2962 (s), 3059 (w), 3620 (w), 3653 (w).

Figure 4: Temperature dependence of the effective magnetic moment of solid 3 with applied field B = 1 T. The red line is a simulation with S = 1 and the parameters given in the inset. B. Quantum-chemical Calculations All DFT calculations were performed with the ORCA program package. [6] The geometry optimizations of the complexes were carried out at either the B3LYP [7-9] or the BP86 [7, 10, 11] level of DFT. Single-point calculations on the optimized geometries were carried out using the B3LYP functional. This hybrid functional often gives better results for transition metal compounds than pure gradient-corrected functionals, especially with regard to metalligand covalency. [12] The all-electron Gaussian basis sets were those developed by the Ahlrichs group. [13, 14] Triple-ζ quality basis sets TZV(P) with one set of polarization functions on the metals and on the atoms directly coordinated to the metal center were used. [14] For the carbon and hydrogen atoms, slightly smaller polarized split-valence SV(P) basis sets were used, that were of double-ζ quality in the valence region and contained a polarizing set of d- functions on the non-hydrogen atoms. [13] Auxiliary basis sets used to expand the electron density in the resolution-of-the-identity (RI) approach were chosen, [15-17] where applicable, to match the orbital basis. The SCF calculations were tightly converged (1 10-8 E h in energy, 1 10-7 E h in the density change and 1 10-7 in maximum element of the DIIS error vector). The geometry optimizations for all complexes were carried out in redundant internal coordinates without imposing symmetry constraints. In all cases the geometries were considered converged after the energy change was less than 5 10-6 E h, the gradient norm and maximum gradient element were smaller than 1 10-4 E h Bohr -1 and 3 10-4 E h Bohr -1, respectively, and the root-mean square and maximum displacements of all atoms were smaller than 2 10-3 Bohr and 4 10-3 Bohr, respectively. Because several broken symmetry solutions to the spin-unrestricted Kohn-Sham equations may be obtained, the general notation BS(m,n) [18] has been adopted, where m (n) denotes the number of spin-up (spin-down) electrons at the two interacting fragments. Canonical and quasi-restricted orbitals, as well as spin density plots were generated with the program Molekel. [19]

z y x d xy 0.01 0.50 O 2 π out of plane 0.50 S total = ½ S Ni = 0 d yz d z 2 d xz d x 2 -y 2 Figure 5. Calculated spin density and frontier orbitals of 1. Figure 6. Calculated structure of 1.

0.12-0.27 0.12 1.26 Overlap S = 0.81 Magnetic Orbitals -0.27 S total = ½ S Ni = 1 Figure 7. Calculation of 1 with tetrahedral Ni. Compund 1 is 19.1 kcal mol -1 disfavoured in comparison to 1.

Figure 8. Calculations of the proposed transient species LNi-O 4 with S = 1/2 vs. S = 3/2 spin state and their spin density.

0.0 0.1 0.0 0.0 1.6 0.0 Figure 9. Calculation of the spin density of LNi(µ-OH) 2 NiL 3. Figure 10. Calculated structure of 3.

Table 1. Cartesian coordinates (Å) of 1 obtained from a geometry optimization at the B3LYP level of DFT. x y z Ni 7.87478 1.82624 10.0454 O 8.45323 0.09615 9.55312 O 7.77149 0.05479 10.67374 N 8.43296 3.10409 8.79901 C 8.16425 4.40602 8.87611 C 7.42319 4.97428 9.92897 C 6.86572 4.2996 11.03099 N 6.97648 2.98461 11.20745 C 6.10955 5.12626 12.05209 C 9.20147 2.57251 7.70448 C 8.67041 5.33584 7.79161 C 8.53399 2.11256 6.53993 C 9.30351 1.55721 5.5071 C 10.68961 1.44793 5.61323 C 11.33062 1.89275 6.76893 C 10.60993 2.45815 7.83121 C 11.35344 2.89924 9.09204 C 11.91252 1.68543 9.86208 C 12.46834 3.92098 8.79535 C 7.01369 2.17412 6.39301 C 6.57106 2.92208 5.12053 C 6.39375 0.76301 6.44322 C 6.39315 2.33984 12.35448 C 7.17075 2.16591 13.52867 C 6.59516 1.4892 14.61413 C 5.29446 0.99055 14.55135 C 4.54577 1.15954 13.38721 C 5.0722 1.82841 12.27205 C 4.22425 1.95849 11.00659 C 2.87007 2.64543 11.27071 C 4.01974 0.58852 10.32827 C 8.61252 2.66288 13.63329 C 9.60655 1.4855 13.68367 C 8.8249 3.61136 14.82902 H 9.77034 5.29502 7.71386 H 8.37133 6.3758 7.99388 H 8.27567 5.04375 6.80372 H 7.2655 6.05221 9.88723 H 5.06554 4.78197 12.14706 H 6.10191 6.19019 11.76952 H 6.56377 5.03229 13.05344 H 8.80753 1.19571 4.6011 H 11.27062 1.00916 4.79572 H 12.41755 1.79162 6.84956 H 10.62672 3.39503 9.7539 H 11.11256 0.96699 10.1131 H 12.39128 2.01039 10.80416 H 12.672 1.14609 9.26634 H 13.27698 3.48391 8.18137

H 12.92442 4.27511 9.73782 H 12.07913 4.80293 8.25638 H 6.61459 2.73306 7.25351 H 6.99884 3.93944 5.07637 H 5.4699 3.01652 5.094 H 6.87923 2.39141 4.20149 H 6.73411 0.14413 5.59236 H 5.29018 0.8218 6.39922 H 6.67262 0.23543 7.37206 H 7.17947 1.34259 15.52792 H 4.86585 0.46403 15.40997 H 3.52973 0.75669 13.34244 H 4.77666 2.59167 10.29526 H 2.22276 2.03991 11.93083 H 2.3252 2.79692 10.3209 H 3.00015 3.63412 11.74663 H 4.98613 0.10787 10.09734 H 3.45774 0.70291 9.38266 H 3.44944-0.10087 10.97802 H 8.83712 3.23611 12.72074 H 9.46077 0.87389 14.59329 H 10.6484 1.8564 13.69011 H 9.48495 0.8207 12.81082 H 8.13342 4.47221 14.79539 H 9.85708 4.00654 14.82678 H 8.6715 3.09749 15.79552 Table 2. Cartesian coordinates (Å) of 1 obtained from a geometry optimization at the B3LYP level of DFT. x y z Ni -0.05053-0.05311 0.014 N 1.8694-0.0177 0.00705 C 2.62479 1.08236 0.01126 C 2.07833 2.38076 0.02274 C 0.71867 2.74949 0.0313 N -0.27021 1.8537 0.0288 O -1.21842-1.39635 0.69081 O -1.22459-1.38706-0.66944 C 2.47741-1.3233-0.00338 C 2.73537-1.96255-1.24387 C 3.28335-3.25374-1.22369 C 3.56522-3.90484-0.02343 C 3.2918-3.2689 1.1869 C 2.74371-1.97828 1.22713 C -1.64573 2.28103 0.03716 C -2.31743 2.44398 1.27666 C -3.66912 2.81829 1.25447 C -4.34739 3.02032 0.05305

C -3.67795 2.83791-1.15646 C -2.32656 2.46393-1.19461 C 4.13515 0.95734 0.00331 C 0.39248 4.22963 0.04395 C 2.41159-1.30851-2.5875 C 1.2637-2.04844-3.30431 C 2.42822-1.34189 2.58121 C 3.67148-1.23541 3.48555 C -1.63185 2.19594 2.62076 C -1.68367 3.42725 3.54609 C -1.65142 2.2365-2.54765 C -2.24405 1.00551-3.2635 C 1.28868-2.09482 3.29784 C 3.64817-1.1955-3.50013 C -1.71038 3.4815-3.45413 C -2.21882 0.95434 3.32278 H 4.48922 0.39003 0.88102 H 4.61658 1.94705 0.0093 H 4.48089 0.4051-0.88729 H 2.7964 3.20144 0.02566 H -0.21254 4.50799-0.83594 H 1.30962 4.83784 0.04555 H -0.20642 4.49402 0.93233 H 3.48912-3.7636-2.16961 H 3.99082-4.91279-0.03125 H 3.50424-3.79051 2.1249 H 2.07214-0.31602 2.39807 H 0.38848-2.15492 2.66193 H 1.01695-1.5805 4.23827 H 1.58976-3.12648 3.55577 H 4.06371-2.2308 3.76127 H 3.42034-0.70837 4.42415 H 4.48952-0.67882 2.99367 H 2.06076-0.28363-2.38911 H 4.47233-0.64854-3.00763 H 3.39186-0.65551-4.42993 H 4.03422-2.18882-3.79157 H 1.55869-3.07828-3.57611 H 0.98721-1.52225-4.23676 H 0.36793-2.11246-2.66249 H -4.20441 2.9491 2.19969 H -5.40197 3.31252 0.05927 H -4.22014 2.98407-2.09548 H -0.58735 2.0206-2.36292 H -2.74824 3.73598-3.73456 H -1.14997 3.30281-4.38986 H -1.27105 4.36767-2.96197 H -2.18166 0.10541-2.62737 H -1.69797 0.80536-4.20403 H -3.3072 1.16445-3.52066 H -0.56925 1.98289 2.42447 H -3.28025 1.10881 3.58954 H -1.66613 0.74108 4.25655 H -2.16026 0.06362 2.67325 H -1.24886 4.32093 3.06361 H -1.11545 3.23484 4.47437

H -2.71927 3.67697 3.83888 Table 3. Cartesian coordinates (Å) of 3 obtained from a geometry optimization at the BP86 level of DFT. x y z Ni 6.64626 12.22222 6.40433 N 6.65448 13.23841 8.08272 N 4.76821 11.6291 6.56463 O 6.94327 12.58441 4.47304 O 8.47547 11.53831 5.89034 C 5.57239 14.63291 9.84694 C 5.51217 13.63505 8.69852 C 4.23641 13.13752 8.37088 C 3.90176 12.09525 7.46872 C 2.51131 11.50147 7.64112 C 7.87193 13.55303 8.78917 C 8.563 14.78277 8.58182 C 9.64225 15.10269 9.43136 C 10.05712 14.23653 10.45024 C 9.41545 13.00015 10.60152 C 8.33093 12.62992 9.78202 C 8.19939 15.75293 7.45786 C 7.93565 17.18977 7.95827 C 9.30827 15.75267 6.38245 C 7.66048 11.27138 10.00269 C 6.80764 11.24673 11.29058 C 8.68214 10.11548 10.00481 C 4.38736 10.5602 5.68141 C 3.60341 10.8312 4.51881 C 3.31407 9.76556 3.64286 C 3.76767 8.4635 3.89455 C 4.50975 8.20613 5.05494 C 4.82548 9.23273 5.96765 C 3.0423 12.22047 4.20716 C 1.49674 12.23735 4.22141 C 3.56013 12.75777 2.85918 C 5.55525 8.88484 7.26522 C 4.65528 8.03845 8.19418 C 6.91117 8.19572 7.01614 Ni 8.78719 12.31684 4.17956 N 8.80254 13.29931 2.53882 N 10.59292 11.69553 4.06677 C 9.84763 14.43027 0.58159 C 9.92571 13.60006 1.854 C 11.1991 13.11864 2.20505 C 11.49893 12.14921 3.18404 C 12.92619 11.62021 3.16575 C 7.56569 13.63249 1.86855 C 6.92368 14.8888 2.0963

C 5.8102 15.23109 1.29858 C 5.31905 14.36398 0.31598 C 5.91967 13.1098 0.14302 C 7.03648 12.71781 0.90626 C 7.40283 15.88202 3.15729 C 7.93758 17.19477 2.54185 C 6.28585 16.19572 4.1779 C 7.63016 11.32455 0.69662 C 7.98856 11.03639-0.77642 C 6.67313 10.24897 1.25606 C 10.97822 10.63279 4.96464 C 11.78048 10.90584 6.1136 C 12.09541 9.83706 6.98252 C 11.65599 8.53396 6.72652 C 10.889 8.27477 5.5802 C 10.53549 9.30126 4.68377 C 12.3292 12.2978 6.43796 C 13.86673 12.29677 6.59963 C 11.67333 12.88353 7.70319 C 9.73571 8.98711 3.41786 C 10.66085 8.85479 2.18637 C 8.84203 7.7401 3.5334 H 6.01672 15.5953 9.51409 H 6.2092 14.26986 10.68192 H 4.55788 14.83851 10.24403 H 3.40529 13.5113 8.98756 H 2.30111 10.68579 6.92257 H 1.73475 12.28872 7.52009 H 2.40004 11.09584 8.67162 H 10.17263 16.05939 9.29089 H 10.89473 14.51407 11.11231 H 9.76033 12.30495 11.38598 H 7.26705 15.38137 6.98109 H 7.15632 17.2187 8.75211 H 7.58922 17.83548 7.11956 H 8.85547 17.65895 8.37427 H 9.41155 14.75035 5.90982 H 10.29327 16.03132 6.82076 H 9.08158 16.4893 5.58021 H 6.97251 11.10386 9.14686 H 6.00038 12.01078 11.26608 H 7.43349 11.43817 12.19221 H 6.32361 10.25224 11.42045 H 9.28966 10.10382 9.07316 H 8.15656 9.13662 10.08006 H 9.38313 10.17625 10.8683 H 2.71104 9.96074 2.73964 H 3.53025 7.64678 3.19246 H 4.84241 7.1758 5.2656 H 3.39646 12.91596 4.99739 H 1.08143 11.86465 5.18168 H 1.07821 11.6033 3.40743 H 1.11746 13.27303 4.06575 H 4.66958 12.74705 2.81323 H 3.21623 13.80285 2.69366 H 3.18817 12.14743 2.00562

H 5.7681 9.83982 7.79262 H 3.69195 8.55237 8.40632 H 5.16333 7.84628 9.16604 H 4.41441 7.05152 7.73836 H 7.58369 8.85172 6.42081 H 6.79299 7.23121 6.47301 H 7.41626 7.97179 7.98206 H 9.22323 15.33812 0.70637 H 9.38591 13.84838-0.24668 H 10.86258 14.7387 0.25912 H 12.03554 13.44286 1.5698 H 13.01798 10.6168 3.62595 H 13.60482 12.3076 3.71904 H 13.30017 11.5678 2.12163 H 5.31935 16.20738 1.44864 H 4.45357 14.65619-0.30227 H 5.51121 12.41534-0.61071 H 8.23805 15.39897 3.70679 H 8.77536 17.01242 1.83522 H 8.3133 17.87255 3.34168 H 7.13934 17.74058 1.9888 H 5.93335 15.27853 4.6985 H 5.40555 16.67335 3.69274 H 6.6566 16.89928 4.95615 H 8.56941 11.26938 1.28512 H 8.68064 11.80256-1.19181 H 7.0864 11.00527-1.42828 H 8.49066 10.04635-0.86224 H 6.46839 10.41468 2.33566 H 7.11455 9.23359 1.13769 H 5.69822 10.25755 0.71896 H 12.70967 10.03506 7.87718 H 11.91562 7.71418 7.41708 H 10.55748 7.24353 5.38185 H 12.07389 12.97242 5.59447 H 14.38223 11.82263 5.73707 H 14.1806 11.7488 7.5164 H 14.24519 13.33951 6.69508 H 10.56963 12.96492 7.60158 H 12.06318 13.90455 7.9085 H 11.88593 12.25734 8.59798 H 9.06855 9.86234 3.2436 H 11.23307 9.78519 1.98914 H 10.06127 8.63132 1.27489 H 11.38996 8.02446 2.3271 H 8.18784 7.78366 4.42898 H 9.43703 6.7993 3.58099 H 8.18545 7.66207 2.6393 H 9.26465 11.38638 6.46199 H 6.48581 13.27103 3.93025

Table 4. Cartesian coordinates (Å) of 4 obtained from a geometry optimization at the B3LYP level of DFT assuming a spin state of S = 1/2. x y z Ni -0.01891-0.00308-0.00249 O 1.64639 0.03145-0.03038 N -1.29543 1.36376 0.00287 N -1.284-1.3808 0.00397 C -2.6208 1.2344-0.00132 C -3.25652-0.01844-0.0042 C -2.61042-1.26575-3.21E-04 C -3.46768-2.51437-5.10E-04 C -0.67666 2.66377 0.00898 C -3.4904 2.4747-0.0024 C -0.34812 3.28313-1.22398 C 0.27041 4.54114-1.1877 C 0.56624 5.16923 0.0217 C 0.25529 4.53651 1.22488 C -0.36366 3.27838 1.24841 C -0.62891 2.59452 2.58849 C 0.69491 2.13571 3.23494 C -1.44527 3.4725 3.55608 C -0.59703 2.60498-2.57007 C -1.40888 3.48445-3.54015 C 0.73504 2.15618-3.20655 C -0.64876-2.67247 0.01094 C -0.32705-3.28202 1.25084 C 0.30982-4.53114 1.22811 C 0.62956-5.16017 0.02529 C 0.32427-4.53749-1.18457 C -0.31217-3.28851-1.22174 C -0.57301-2.61597-2.56835 C -1.37287-3.50902-3.53596 C 0.75103-2.14784-3.20764 C -0.60395-2.6021 2.59055 C 0.71193-2.12471 3.23977 C -1.40959-3.49188 3.55638 H -3.28939 3.09903 0.88547 H -4.55805 2.20546-0.00877 H -3.27977 3.10438-0.88418 H -4.34715-0.0229-0.00836 H -3.251-3.14221-0.88219 H -4.53803-2.25601-0.00658 H -3.25998-3.13633 0.88752 H 0.53553 5.03683-2.12622 H 1.05019 6.15061 0.02665 H 0.5087 5.02861 2.16852 H -1.22364 1.68793 2.39424 H 1.26357 1.47963 2.55289 H 0.49657 1.57746 4.16885 H 1.33729 2.99972 3.48666 H -0.89329 4.38155 3.85524 H -1.67819 2.91095 4.4792

H -2.40171 3.7954 3.10672 H -1.18902 1.69447-2.38612 H -2.37152 3.79909-3.09824 H -1.62945 2.92747-4.46905 H -0.85902 4.39844-3.82798 H 1.37494 3.02474-3.44891 H 0.54777 1.60161-4.14495 H 1.30088 1.49977-2.52246 H 0.57006-5.01909 2.17203 H 1.12722-6.13469 0.03082 H 0.59569-5.03041-2.12274 H -1.17847-1.71434-2.38467 H -0.80964-4.41491-3.82361 H -1.60353-2.95674-4.4652 H -2.32985-3.83773-3.092 H 1.30719-1.48047-2.52621 H 0.55376-1.59871-4.14717 H 1.40443-3.00671-3.44839 H -1.21108-1.70402 2.39527 H 1.36671-2.97938 3.49127 H 0.50369-1.57079 4.17409 H 1.27183-1.45903 2.55978 H -2.36056-3.82793 3.10506 H -1.65217-2.934 4.47922 H -0.84542-4.39321 3.8562 Table 5. Cartesian coordinates (Å) of 4 obtained from a geometry optimization at the B3LYP level of DFT assuming a spin state of S = 3/2. x y z Ni 0.05324-0.00112 0.00613 O 1.69333 0.01616 2.37E-04 N -1.21785 1.47067 0.0061 N -1.20168-1.48523 0.00721 C -2.53618 1.26433 8.04E-04 C -3.12868-0.01784-0.00191 C -2.52242-1.29327 1.69E-03 C -3.44358-2.49838-2.69E-04 C -0.67416 2.80246 0.00947 C -3.47066 2.45915-0.0018 C -0.36782 3.43275-1.22334 C 0.21281 4.70932-1.19033 C 0.49079 5.34924 0.01698 C 0.19652 4.70974 1.22072 C -0.38444 3.43319 1.24616 C -0.63698 2.74395 2.58669 C 0.69103 2.27098 3.21378 C -1.43498 3.61929 3.57149 C -0.60367 2.74465-2.56743 C -1.40231 3.61627-3.55518 C 0.73287 2.28517-3.18638

C -0.64355-2.81109 0.01143 C -0.34718-3.438 1.24849 C 0.24764-4.70816 1.22383 C 0.54885-5.34514 0.02048 C 0.26399-4.709-1.18723 C -0.33046-3.43884-1.221 C -0.57412-2.75413-2.56539 C -1.36075-3.63599-3.55366 C 0.75692-2.27766-3.1834 C -0.60759-2.7507 2.58846 C 0.71473-2.26026 3.21419 C -1.39384-3.63499 3.57471 H -3.30074 3.09391 0.88551 H -4.52456 2.14117-0.00899 H -3.28986 3.09885-0.88334 H -4.21976-0.02373-0.00673 H -3.25575-3.13643-0.88155 H -4.50097-2.19212-0.00753 H -3.26656-3.13085 0.8873 H 0.46056 5.21137-2.1303 H 0.94503 6.34465 0.01986 H 0.43171 5.21201 2.16375 H -1.2412 1.84321 2.39475 H 1.24507 1.6085 2.52509 H 0.50317 1.71565 4.15165 H 1.34671 3.12865 3.45246 H -0.87109 4.51821 3.8789 H -1.66751 3.04872 4.48916 H -2.39059 3.95813 3.13238 H -1.20142 1.83813-2.38249 H -2.36446 3.9444-3.12232 H -1.62221 3.04727-4.47694 H -0.84437 4.52173-3.85418 H 1.38262 3.14911-3.41868 H 0.55617 1.73097-4.12707 H 1.28749 1.62544-2.49556 H 0.48806-5.20738 2.16715 H 1.01358-6.33571 0.02392 H 0.51703-5.20901-2.12686 H -1.18357-1.85536-2.38095 H -0.79099-4.53414-3.85244 H -1.58745-3.06986-4.47553 H -2.31886-3.97649-3.12141 H 1.30242-1.61037-2.49253 H 0.57387-1.72622-4.12451 H 1.41798-3.13326-3.41456 H -1.22329-1.85793 2.39588 H 1.38152-3.10931 3.45283 H 0.52044-1.7067 4.15178 H 1.25976-1.59111 2.52471 H -2.34535-3.98632 3.13652 H -1.63307-3.06638 4.49187 H -0.81845-4.52636 3.88285

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